Stationary But Powering Forward

Fuel cells are an evolving technology and a current new market for the electrical contractor (EC). As a result of research and development, fuel cells have become feasible to implement with greater capacity, reduced costs, increased reliability and improved efficiency.

A variety of applications may be suitable for fuel cells, especially those that take advantage of their unique operating characteristics and capabilities. For example, small fuel cells may replace traditional batteries in mobile devices, such as laptop computers, cellphones and even implanted medical devices. Similarly, fuel cells could also replace the rechargeable batteries and internal combustion engines in vehicles.

Truthfully, we may be witnessing the dawning of a whole new era for electricity off the grid. But most important for electrical contractors, the use of fuel cells as the primary, supplemental or backup power sources for residential, commercial, institutional, industrial, infrastructure, and utility facilities and installations presents a potentially huge market. Typically, these installations employ “stationary fuel cells.” The market is there and growing. All the EC may need is an introduction to the possibilities.

What are fuel cells?
Fuel cells use an electrochemical process to convert the stored energy in a continuously supplied fuel into electrical energy that can power a connected load. The energy-conversion process usually involves combining hydrogen as the fuel with oxygen in the air to produce direct current (DC) electricity and water. While all fuel cells will operate using hydrogen as their fuel source, some can operate using methane as a direct fuel; it depends on the construction and operating characteristics.

Fuel cells, like batteries, have a positive and negative terminal and an electrolyte. However, unlike batteries, which require recharging or replacement after expending their charge, a fuel cell is an electrical energy-production device that never needs recharging and continues to power its load as long as fuel is supplied and oxygen is available. In this regard, a fuel cell is like a traditional internal combustion, gas turbine or steam-powered generator, although the energy-conversion process does not involve combustion, and there are no emissions. As a result, fuel cells are environmentally friendly and, if they are using a renewable-fuel source (such as methane from a landfill), they are considered renewable-energy sources like photovoltaic (PV) systems and wind generators. Furthermore, being categorized as a renewable-energy source makes a fuel-cell installation eligible for the same or similar government and utility financial incentives.

Many fuel-cell types are under development, but only a few are commercially available and used in stationary applications. Fuel cells are typically categorized by their electrolyte, which in turn determines the internal chemical reactions that govern the operating characteristics. The three most common fuel-cell types currently- marketed for stationary applications are proton exchange membrane (PEMFC), solid oxide (SOFC), and phosphoric acid (PAFC). While it is not necessary for the EC to understand the electrochemical process to install a fuel-cell system, it is important to know the fuel-cell types and their operational characteristics when selecting a fuel-cell system for a design/build project. Design/build customers may require education on fuel-cell systems, and they may look to you for those details. To get the information, take advantage of training opportunities from manufacturers on their specific fuel cells and systems.

The fuel-cell system
An individual fuel cell can only produce a small amount of voltage and a limited amount of electric power; however, if you combine multiple cells, you get building blocks for a fuel-cell system. To produce the necessary voltage, current and power for a stationary fuel-cell application, fuel cells need to be connected in series, like batteries or solar cells, into a stack. This stack is the key component in a fuel-cell system because it produces the electrical energy.

However, the fuel-cell stack will only produce unregulated DC power when supplied by specific fuels at required purities and pressures. For most fuel-cell types, the fuel supplied to the fuel-cell stack will need to be pure hydrogen. Therefore, to be a practical stationary fuel-cell system, the stack needs additional mechanical and electrical subsystems referred to as the “balance of system” (BOS) that, at a minimum, will include a fuel processor at the input and a power conditioner/inverter at the output.

It is not practical to use hydrogen as the fuel for most stationary fuel-cell installations. Instead, it is safer, more practical and cheaper to use natural gas, propane or another readily available hydrocarbon fuel or methane from landfills, biomass or other renewable fuels. These alternative fuels typically require a fuel processor that includes a “reformer.” A reformer extracts hydrogen from the hydrocarbon fuel, leaving carbon compounds, such as carbon dioxide, which is referred to as a “reformate.” However, some fuel cells, such as SOFCs that operate at high temperatures, often use these alternative fuels directly without external reformation. The fuel processor will typically include a filter that will remove impurities, such as sulfur, from the fuel that can damage the fuel-cell stack.

The unregulated DC power at the output of the fuel-cell stack needs to be converted to a usable voltage by either a power conditioner or a power inverter. A power conditioner would supply the required regulated DC voltage directly to DC loads, such as electronic communications and data processing equipment. More commonly, a power inverter is included as part of the fuel-cell system to convert the unregulated DC power supplied by the fuel-cell stack to alternating current (AC) that matches the load requirements or the customer’s distribution system voltage in frequency, number of phases and quality. This setup is similar to other alternative power sources.

For residential and small commercial buildings the fuel-cell system output typically would be 120/240-volt (V), single-phase, and for larger commercial and institutional installations, the output typically would be 480Y/277V, three-phase, 4-wire. In addition, if the fuel-cell system is used as an interactive system connected in parallel with the utility power supply, antiislanding protection will be required to protect utility workers from back-feed when restoring service after an outage.

Fuel-cell system installation
With stationary fuel-cell systems, the manufacturer supplies an integrated stack and the balance of system components. Fuel-cell systems used for residential, commercial and institutional buildings are often modular and supplied as a “black box.” The EC makes the electrical connection to the fuel source at the input; to the customer’s distribution system; and to any required air supply system, water recovery and reformate waste-collection systems, combustion gas exhaust systems, or waste-heat exhaust or recovery systems. For larger fuel-cell systems used for industrial and utility installations, the fuel-cell system still will be supplied as a package, but it may be provided in pieces that the manufacturer or EC needs to assemble in the field.

Combined heat and power
The efficiency of a fuel-cell system installation along with the associated return on investment will improve greatly if waste heat from the fuel-cell system is recovered and used in a combined heat and power (CHP) system. The waste heat can be captured and harnessed to reduce the customer’s energy use by producing hot water, steam or heating for occupant use, thermal comfort or production processes. For example, a fuel-cell system could be coupled with an absorption chiller that uses hot water or steam to produce chilled water for thermal comfort, refrigeration or process use. If the EC does not have the internal expertise to design and install a CHP system on a design/build project, it can team up with an HVAC or mechanical contracting firm.

Diversifying into the fuel-cell market
Demand for stationary fuel-cell installations will continue to increase as the technology matures and facility owners and operators become aware of their advantages. Fuel cells are becoming increasingly reliable and economical, putting them in direct competition with utility-supplied power. Furthermore, a fuel-cell plant can expand with the facility’s load. These systems are able to use a variety of fuels and are environmentally friendly and quiet.

If the EC wants to diversify into this market, it should first look at its market area and determine which stationary fuel-cell characteristics could address the current and future power supply concerns of local facility owners and operators. With this information, the electrical contractor can then identify fuel-cell system manufacturers whose products can best address its potential customers’ needs and partner with them, while also using this partnership to get properly trained and educated about the systems. The EC can then develop a marketing program to educate potential customers about the advantages of fuel cells and how they can help alleviate concerns about their facility’s power supply.

Thanks to ELECTRI International Inc. for sponsoring “Energy Roadmap: Electrical Contractor’s Guide for Expanding Into the Emerging Energy Market,” on which this article is based.

GLAVINICH is director of Architectural Engineering & Construction Programs and an associate professor in the Department of Civil, Environmental and Architectural Engineering at the University of Kansas. He can be reached at 785.864.3435 and tglavinich@ku.edu.